Dissolution of gas

Abstract

Liquid in which oxygen-containing gas is to be dissolved is pumped through a main and distributed into faster-moving subsidiary streams. Each subsidiary stream passes through a turbulence-inducing means and air or oxygen is introduced into the turbulent region of alternate streams. The relative proportions of air to oxygen introduction are varied so as economically and efficiently to oxygenate the liquid. The gas-containing liquid passes through nozzles back into the volume of the liquid at sufficient velocity to cause further turbulence, making gas bubbles shear into smaller bubbles and also agitating the body of liquid.

What is claimed is:  
     
       1. A method of dissolving oxygen-containing gas in a volume of liquid having a variable oxygen demand comprising pressurising the liquid, forming a main stream of the liquid, distributing the main stream into a plurality of subsidiary streams each having a velocity greater than that of the main stream, passing each of the subsidiary streams through means configured to create turbulence therein, introducing gas into the turbulence and introducing the gas-containing subsidiary streams into the volume of the liquid at a velocity sufficient to create further turbulence causing bubbles of said gas to shear into smaller bubbles, characterised by introducing oxygen into a first set of the subsidiary streams and air into a second set of the subsidiary streams, by sensing the instantaneous oxygen demand in the volume of liquid, and by maintaining constant the rate of introduction of said air and varying the rate of introduction of said oxygen in response to said sensing to meet the instantaneous oxygen demand of the liquid. 
     
     
       2. The method as claimed in claim  1  characterised in that the velocity of flow of the main stream is in the range 2 to 4 feet per second. 
     
     
       3. The method as claimed in claim  1  characterised in that each subsidiary stream is introduced into said volume of liquid in the form of one or more jets, each having a velocity in the range 30 to 65 feet per second.